Absorption refrigeration systems, which are driven by heat energy, have been long known and indeed predate mechanical expansion refrigeration; but the latter has become more prevalent due to abundant and inexpensive electrical energy and the discovery and commercial production of fluorinated hydrocarbon refrigerant gases. However, increasing costs for electrical energy, especially during high demand portions of a calendar day, and environmental concerns associated with fluorinated hydrocarbons are creating opportunities for absorption refrigeration.
In an absorption refrigeration cycle a liquid solution, such as lithium bromide in water, is concentrated in a first phase by heating to drive off a portion of a diluent component (water) and the concentrated solution is delivered to a second absorber phase where it absorbs or reabsorbs that component so as to become diluted. Thus, the diluent component (such as water) is available between phases to take up heat removed from a load (such as refrigerated or cooled space) so as to produce a diluent vapor and that vapor is then absorbed by the concentrated solution which, upon becoming diluted is returned to the first phase to be reconcentrated.
Heretofore absorption refrigeration systems have been relatively inefficient and inflexible because they have largely relied on the refrigeration effect of an expandable absorption component and the requisite heat energy has been supplied either by unreliable waste heat or by a burning flame of expensive fuels; and the respective concentrator and absorber phases have not been adaptable to intermediate storage whereby the concentrator phase could be disassociated, timewise, from the absorber phase. However, in U.S. Pat. No. 4,269,041 to Gunther Holldorff, there is described an ammonia absorption refrigeration system with time separation facilitated by storage of the absorption fluids.